Temperature Field Analysis And Experimental Study On Laser Cladding Of Helical Gear

Laser cladding is a kind of surface engineering technology that can use laser irradiation to produce excellent wear resistance,corrosion resistance,heat resistance and other properties surface.The metallurgical combination between clad coating and matrix can be formed.Therefore,it is especially fitting for repairing the high precision parts.And this technology is becoming to be an important method in the area of remanufacturing of machine parts.Numerical calculation is the foundation of theoretical researching.The temperature field of laser cladding were calculated and analyzed.Moreover,the special laws of temperature field and when cladding on teeth surfaces of gear shaft were analyzed.Calculation results show that the laser energy imported into the gear shaft would be concentrated inside the tooth mostly in the process of laser cladding on tooth surface.The distribution of temperature field around the laser beam is non-uniform.The isotherm lines at the side of tooth-tip are penetrated into the interior of gear.But the isotherm lines at the side of tooth root are distributed quite dense.So large temperature gradient would be presented at this region.In addition,in the practical application of laser cladding technology,a single beam cladding experiment was carried out for the gear shaft.The experimental results are in agreement with the calculated results,and there is a problem that the tooth top is excessive melted and the stress of the tooth root is too concentrated.During the single-beam laser cladding of helical gear teeth,there are a few problems,such as excessive melting of the tooth top,extremely dense isotherm at the tooth root,large temperature gradient,easily cracked cladding layer.In this paper,multi-beam cladding is employed for the tooth surface repair.A finite element method is used to analyze the temperature field of the laser cladding process with different beam number and energy distribution.The results show that the temperature distribution is more uniform and the maximum temperature at the tooth top decreases significantly when cladding with multi-beam distribution.The collapse of the tooth top and the excessive temperature gradient at the tooth root can be avoid.Two and three beams with even and uneven energy distribution are investigated.The results show that the leading beam increase the overall temperature of gear teeth,and the heat generated by the following beam can clad and also slow down the cooling rate of the tooth.Hence,the temperature distribution in the tooth is more even and the temperature gradient at the tooth root is reduced.As a result,the internal stress level after cladding is decreased favorably.The multi-beam laser cladding system is designed and the multi-beam cladding optical path design is completed,which is ready for the future multi-beam experiment.